This invention relates generally to audio and/or video data and more particularly to copy protection of such audio and/or video data.
Unauthorized copying of copyrighted works is, unfortunately, very prevalent in our society. Such unauthorized copying ranges from simple copying of a few pages from a copyrighted book to black market distribution of millions of dollars worth of illegally copied movies, compact discs, and other entertainment medium.
With the advent of DVD, the illegal copying of DVD""s is of great concern to content companies (i.e., the companies owning the copyrighted work recorded on the DVDs). To protect the copyrighted works, content companies are demanding that DVD produces incorporate a security mechanism to prevent unauthorized copying. One such security mechanism is currently being used in conjunction with video cassette recorders and was developed by Macrovision.
The Macrovision anti-taping technique (herein after referred to as Macrovision) works due to the differences in the way VCRs and televisions operate. The automatic gain control (AGC) circuits within a television respond slowly to change, while a VCR""s AGC respond quickly to change. Macrovision takes advantage of this difference by modifying the video signal so that a television will still play it properly, while a VCR will not record a viewable picture. Macrovision accomplishes this by utilizing at least one of Sync pulse adjustment, vertical blanking pulses, and end of field pulses. This technique is being contemplated as an adequate part of a solution for copy protection for DVDs.
While Macrovision prevents VCRs coupled to televisions from making quality copies, it does not prevent unauthorized copying when a VCR, or any other video source (including a DVD player), is coupled to a personal computers (xe2x80x9cPCxe2x80x9d). As is generally known, a PC may be equipped with an analog video decoder, such as the All-in-Wonder, manufactured by ATI Technologies, Inc., which converts an analog video signal into a digital video data stream, where the analog video stream originated from a video source, such as a DVD player. Such an analog to digital conversion strips out the Macrovision encoding. As such, a DVD player sourcing the analog video to the PC may have the copyrightable work copied without the Macrovision encoding. Such unauthorized copying is unacceptable to content companies.
Therefore, a need exists for a method and apparatus that detects the presence of encoded copy protection information embedded in a video data stream such that a PC cannot make quality copies of the video data.